Optics and Beam Analysis Tools
From APEXwiki
This page lists tools that are needed for online beam monitoring and optics analysis. Please edit/add additional needed tools. This page should serve as both a status report and basic documentation for the analysis tools for shift-takers, so please document briefly in the appropriate section below.
All tools that are ready should be demonstrated in a subdirectory of the APEX analysis directory /work/halla/apex/disk1/ and briefly documented here.
Contents |
PREX Target Configuration
Optics Target
- Five carbon foils, which are 99.5% chemically pure.
- Upstream face of each foil located at 0 cm, +/- 7.5 cm and +/- 15 cm.
- The fourth foil (+7.5 cm) is missing after the first target chamber vacuum issue: See Halog 316718.
- 42 +/- 1 mg/cm2.
Sieve Slit
Sieve-slit installed for PREX showing acceptance due to Q1 entrance collimator:
- The sieves are 0.5 cm thick tungsten plates.
- Most holes are 1.4 mm in diameter with two larger holes at 2.7 mm in diameter.
- Blue circles represent original holes used for the superconducting septum magnets (circa 2003-2005).
- Red circles represent holes drilled for PREX.
- Dotted Magenta line represents the expected PREX acceptance with the PREX tune.
Optics Optimization
We can use Jin Huang's HRS Optics Optimizer (see Reference Guide).
A copy of this optimizer has been setup at working disk /work/halla/apex/disk1/Optics_JinHuang. Some example data from Transversity is also copied over for test purpose. For example one can already run "analyzer LOpticsOptScriptVertex.C" to optimize vertex z for this test data.
Work Flow
Tg_Y : replay_det_L.C -> cut_L_Vertex.C -> VertexTree2Ascii -> LOpticsOptScriptVertex.C -> Check Tg_Th, Tg_Ph : replay_det_L.C -> cut_L.C -> SieveTree2Ascii -> LOpticsOptScript.C -> Check Tg_Dp : replay_det_L.C -> cut_L_dp.C -> DpTree2Ascii -> LOpticsOptScriptDp.C -> Check
Example Output (Including plot/log/database) using Transversity Data
Tg_Y : OptVZ/db_L.vdc.dat.18.CentralFoilInvX* Tg_Th : OptTh/db_L.vdc.dat.16.MidPlnSym* Tg_Ph : OptPhi/db_L.vdc.dat.14.MoreTerm.NoT310* Tg_Dp : OptDp/db_L.vdc.dat.17.MidPlnSym.RevRadLoss.ReOptimized*
Beam Monitoring
Most of these histograms are closely related to those already existing in spot++
x and y Beam position monitoring
This already exists in spot++ but target x and y will need to be modified to account for the offset from corrector magnet, if the magnet is placed in front of the target (corrector magnet contact: B. Wojtsekhowski).
Beam position for events in small z range
(Spot++ distributions, but after selecting events based on HRS-reconstructed target z).
Optics/Target Monitoring
require particle ID cut (to remove pions in 2-pass beam optics monitoring)
1D reconstructed event distributions
- Z positions shown with expected positions
- Spectrometer momenta
- Angle between left and right HRS
2D sieve slit reconstructed event distributions
- Positions in the sieve-slit plane
- theta_target and phi_target with cut on Z.
2D histogram of z from L-arm HRS and R-arm HRS
For coincidence-trigger events, should have correlation.
Reference
Available datasets for developing and testing these tools
E06-002 PREX
Available Tools
Hall A Root/C++ Analyzer
Online GUI How To Documentation
Jin Huang's HRS Optics Optimizer Reference Guide
Bob Michaels' Spot++
